Hydrocarbon drying oil production



tates FYDRGCARBGN DRYING GIL PRODUCTION Application Idarch 5, 1954, Serial No. 414,328

4 Claims. (Cl. 269-669) This invention relates to a process for making a drying oil or varnish by polymerization of a diolefin such as butadiene in the presence of sodium and is a continuation-in-part of application Serial No. 134,714, filed December 23, 1949.

Drying oils of excellent quality can be made by polymerizing 109 parts of butadiene monomer, or particularly by copolymerizing about 75 to 85 parts of butadiene-1,3 and about 25 to 15 parts of styrene at 25 to lGO" O, preferably at 65 to 85 C., in the presence of about 50 to 500 parts of an inert hydrocarbon diluent boiling between about and 250 C., or preferably between 50 and 200 C., such as pentane, benzene, cyclohexane, naphtha or mineral spirits. Where low boiling materials are used, it is desirable to operate under suflicient pressure to maintain the charge in liquid phase, e. g. under pressures ranging from 1 to atmospheres. About 0.1 to 16 parts, preferably about 1 to 3 parts of ely divided sodium metal is used as catalyst. Certain ug agents, e. g. about to 56 parts of dioxane and c lyst activators, e. g. l to per cent of isopropyl alcohol based on the Weight of sodium, are also preferably added to the reaction mixture to assure the production of a colorless oil and to shorten the reaction time. Throughout this specification, all references to proportio s materials are expressed in parts by Weight, unless 1 otherwise. fhen the reaction has reached the desired conversion, 2v .ich may be about 50, or preferably the t is destroyed and converted into an easily filtrable salt by additatn of an essentially anhydrous monooasic sat rated C1 to C5 organic acid which is soluble in the carbon mixture. The acid, such as formic, acetic -ntanoic, is added directly to the crude reaction prodt and the resulting sodium salt is thereafter separated the crude product by filtration. Then the crude ltrate is fractionated to remove the promoting and actiagents as well as any unreacted monomer and p reer in the product to the desired level, which may be between about 30 and 99% non-volatile matter.

Unlike natural drying oils the resulting product is useful as a varnish without requiring any further treatment or pur oses of bodying or the like, but nevertheless it is often desirable to subject the product to a heating step for about 3-9 to 2&0 minutes at about to C. where-- by certain properties such as gloss of the films derived from the oil are improved. It is particularly advantageous to carry out the heating step in the presence of a small amount of a polar compound such as maleic anhydride, acrylonitrile or thioglycolic acid.

The catalyst used is in the form of finely divided particies having an average particle size of less than 200 microns, e. g. between 1 and 100 microns, preferably between it and 50 microns. When catalyst of such dded size is used, then the amount of catalyst at i exceed 2.0% by weight. This is unexpected it is generally considered that the production of Fatented July 5, 1955 liquid polymers requires the use of large amounts of catalyst. The catalyst may be any one of the alkali met ls, such as sodium, potassium or the like.

When adapting the process to continuous operation it is desirable to maintain an essentially constant quantity of material in the reactor into which the feed streams are introduced. The addition and withdrawal of materials is at such a rate as to permit the formation and maintenance of polymer in a concentration of at least about 8 /s% by weight in the reaction mixture at a conversion of 50% when the maximum amount of solvent is used. At 100% conversion the reactor concentration will vary between 15 and 66 /2, weight percent depending on the amount of solvent present.

It is the principal object of the present invention to devise irrorc-ved process for the sodium polymerization of bntachenoid drying oils on an industrial scale. This and other objects will appear more clearly from the subsequent description wherein the accompanying drawing schematically illustrates the preferred equipment and flow sheet involved in carrying out the invention.

Referring to Figure l, the reaction mixture is preferably made up in blending tanlc 1 into which butadiene, styrene, isopropyl alcohol, the ether promoter and straight run mineral spirits or other hydrocarbon diluent are introduced in the desired proportions. The reaction monomers and make-up quantities of the alcohol are introduced to tank 1 from conventional storage facilities not shown and further amounts of the alcohol, ether and the hydro .rbon diluent are introduced to tank 1 through recycle one it) which leads from the recovery equipment described later. After the materials have been properly mixed in tank 3. by means of stirrer 2, a stream of the resulting mixture is withdrawn through line 3- to reactor 4-.

This reactor may be simply a one-stage equilibrium reactor from which the polymerized product is continuously withdrawn therefrom after a certain residence time or it be a coil connected to a reactor provided with a stirrer, or a single coil having the necessary length to give the desired reaction. Thus the reaction may be carried out in a single vessel or in a plurality of vessels with partial conversion in all but the last vessel. Prior to entering reactor line 3 may be joined by line 5 through which sodium catalyst is introduced into reactor preferably in the form of a slurry of finely divided catalyst particles in mineral spirits or other suitable hydrocarbon liquid. Alternatively, catalyst line 5 may enter the reactor separately. instead of mixing the styrene monomer into the feed in tank 1, it may be introduced directly into reactor 4 by a separate line as will be described later.

For the batch process p-dioxane has been found to be the outstanding pr motor While ethyl ether is superior for the continuous process. In general straight chain mono or diet-hers of 2 to 8 carbon atoms, and the cyclic diethers having the oxy n atoms separated by at least two carbon atoms are suitable. Examples of such ethers include diethyl ether, diethyl acetal, diethyl ether of ethylene glycol, dioxane, etc.

After a reaction or residence time sufiicient to allow for the desired conversion of monomers, which time may range between about 10 minutes and 10 hours depending principally on size and design of reactor, reaction temperature, catalyst concentration and particle size, the crude reaction product is withdrawn from reactor 4 through line 6 which leads to diluent treating drum 7 which contains stirrer and a suitable cooling device such as internai coi 8 capable of removing any undue heat of reaction that may be generated in this zone. In this drum the partially spent sodium catalyst contained in the reaction mixture is utilized as a treating agent to remove or destroy all water and other inhibiting impurities that are or may be present in the make-up hydrocarbon and the other materials which are introduced into drum 7 through line ll. Although the introduction of the diluent and other mat rials at this point somewhat increases the load on the fractionation equipment used in the recovery step described later, this or an equivalent pretreatment of the diluent with sodium is one of the essential elements of the present process in that it is surprisingly effective in improving the overall eliiciency oi the system, as opposed to a process wherein untreated make-up materials are fed directly to the reactor. This is particularly true as regards pre-treating the hydrocarbon diluent, which constitutes the predominant fraction of the make-up streams in view of the fact that a substantial proportion of the diluent is eventually withdrawn in the final product. Conversely, in view of the relatively minute amount of dioxane required in the make-up stream solely to compensate for losses, it is feasible to introduce the latter into the reaction without pre-treatment. The addition of the hydrocarbon diluent into drum 7 has the further advantage of facilitating subsequent flow and filtration of die crude polymerization product which is quite viscous when cold, unless suitably dilute .,Water contained in the make-up diluent reacts with the sodium catalyst in drum 7 and liberated hydrogen is withdrawn overhead through line 12. The crude product, diluted with an amount of make-up hydrocarbon solvent approximately compensating for the amount of solvent contained in the finished product, is withdrawn from drum '7 through line 13 to another drum 14 provided with cooling device 15 and agitator 16. A slight excess of anhydrous acetic acid is continuously introduced into drum 14 through line 17 in order to react with the remaining sodium catalyst and thereby convert it into sodium acetate which is an inert, easily filtrable salt. Hydrogen gas produced in this reaction is removed from acid treating drum 14 through line 18. From drum 14 the acidified crude product is continuously transferred through line 19 to drum 2i; also preferably provided with a cooling device 21 and agitator 22. In drum the small amount of excess free acid is neutralized with ammonia gas which is bubbled in through line 23. A suitable filter aid such as lrieselguhr or iullers earth is also introduced into ammonia treating drum 2% so as to facilitate subsequent filtration of the salts from the product. It is particularly convenient to add the filter aid in the form of a thick slurry, e. g. as a dispersion in the same kind of hydrocarbon used as reaction diluent.

From drum 2d the crude product is withdrawn through line 24 and passed through conventional filtration equipment such as a filter press or even a continuous rotary vacuum filter 25. Efficient use of the latter is possible due to the crystalline form of the filtrate obtained when operating in accordance with the novel process. The filtered product is then run oi to storage drum 25 which serves to smooth out any undue variations in flow rate. Prom drum 26 the filtered product is fed continuously to distillation tower 27 which removes excess ammonia as an overhead stream 28, concentrates a bottom stream 29 containing the oily polymer of the preferred concentration of about to 70% polymer in hydrocarbon diluent, and allows the withdrawal of a vapor side stream 47 which contains dioxane, any residual isopropyl alcohol as well as excess hydrocarbon diluent. The vapor stream 47 is condensed, passed to storage tank 43 and eventually recycled to blending tank 1 through line 40.

The ammonia stream 28 is recycled to treating tank 20 after being supplemented with fresh ammonia stream 23. Product stream 29 is preferably passed through heat treating drum 30 where the drying oil is kept for about 30 to 120 minutes at a temperature of about 120 to 250 C., preferably about 150 C., in order to improve the gloss coil or other suitable heating device adapted to maintain the contents at a temperature of about 40 C. or in order to maintain the viscous product in a tare sufficiently fluid for withdrawal.

Furthermore, all or a part of the product may be tapped or? through line 3-4 to be concentrated further to a concentration between 86* and 99%, preferably between and 98%. This can be done by any convenient means, as for example, by stripping the hydrocarbon solvent from the more dilute product by circulation through baflle drum 35', return line 36 and heater 37, at a temperature of about C. to 200 C. under reduced pressure of about 0.5 to 2 lbs/ sq. inch absolute. The concentrated duct is "nally withdrawn from the bottom of the tower through line 33 and cooler 39 to storage tank 40, preferably maintained at about 90 C. to maintain the oCOSllY of the product in a range permitting easy pump- The hydrocarbon solvent stripped overhead is passed through line ll and water cooler 42 to separating drum 43 whereirom the condensed, dry hydrocarbon solvent is recycled either through lines 44, 44a and 11 to solvent treating drum 7, or through lines 44, 44b and directly to blending tank 1. The vacuum necessary for the stripping operation can be obtained readily by means of the illustrated arrangement consisting of asplrator line 45 connected to a suitable steam jet ejector which turn is connected to condenser 47.

Alternatively, instead of concentrating the oily polymer in drum 35 as describ-.d above, the drum may be replaced by a multiplate stripping tower operated underproper conditions, e. at a temperature of about l50 C. and a pressure of 0.5 to 2 lb./sq. inch absolute; the use of a rziitable stripping gas such as methane improves the ethciency of the tower.

The hydrocarbon diluent, alcohol and dioxane-containiru vapor e stream 47 withdrawn from principal fractionation tower 27 is recycled through storage tank 43 and return. lines 4% an it, to blending tank 1.

The following example is offered to illustrate the invention, and it will be understood that all of the specific conditions and limitations given are not necessarily co-extensive with the broad scope of the invention as defined in claims.

Example 1 was mixed with cc. of a tinedispersion of 52.5 g. of sodium in 19,0 g. of Varsol. The sodium dispersion was prepared by melting the sodium under Varsol at 110-125 C. and stirring with an Eppenbach l-lcmornixer for about 30 seconds. After one hour batch reaction time in a two liter turbomixer, fresh feed and sodium dispersion were added continuously at 30 cc./min. and 2.6 cc./rni.n. respectively. The turbomixer was maintained at 70 C., and the product overfiowed into a coil at 9798 C. The amount ofsodium used was about 1.4 percent on monomcrs. Hourly samples were obtained by quenching the product with a slight excess of acetic acid, filtering, and

stripping under vacuum to ill-30 percent non-volatile material. The N. V. M. was determined on each sample and the following yields calculated:

Sample No. 1 Polymer, wt. gg i f gg' Samples 1 and 6 were restripped at 5 mm. and adjusted to 50% N. V. M. in Varsol, and the drying rate and chemical resistances of films made therefrom were determined. The following results were obtained:

Drying rate, hours (air dried) Cut Rating: 9wet', 8verystlcky; 7*film just clings to finger; 6-sc touch; 3decided tack, but dust free; Odry, tack free.

Chemical Resistance (air dried) W G S C F 4 0 O O 2 2 0 O 0 5 Code: W-water resistance; Ggrease resistance; S-s0ap resistance; G-caustic resistance; FFlex.

Scale: DUnanected; 9failure.

The nature of the present invention having been thus fully set forth and s ecific examples of the same given,

carbon solvent containing butadiene and polybutadiene in a closed reaction vessel at a temperature ranging from to C., introducing butadiene, hydrocarbon solvent, and catalyst into said body of liquid reaction mixture and Withdrawing equivalent quantities of reaction mixture therefrom to maintain an approximately constant volume at a rate permitting the formation and mair1- tenance of polybutadiene in a concentration of at least 8 /3 weight percent but not in excess of 66% weight percent in said reaction mixture exclusive of butadiene, the quantity of catalyst employed being not in excess of 2.0 parts by Weight per 100 parts total butadiene feed employed, deactivating alkali metal in said solution, and recovering a clear low-color liquid polybutadiene-polymer in dissolved form.

2. Process according to claim 1 in which styrene s admixed with the butadiene feed the quantity of catalyst employed being not in excess of 2.0 parts by weight per 100 parts total monomer feed employed, and a liquid butadiene-styrene copolymer is produced.

3. A continuous method for the production of liquid polybutadiene which comprises continuously maintaining m approximately constant volume of reaction mixture comprising a highly agitated stable dispersion of finely divided sodium metal catalyst having an average particle size of less than 200 microns in a body of liquid hydro carbon solvent containing 1,3-butadiene and polybutadiene in a closed reaction vessel at a temperature ranging from 50100 C., introducing 1,3-butadiene feed, hydro carbon solvent, and catalyst into said body of liquid reaction mixture and withdrawing equivalent quantities of reaction mixture therefrom to maintain an approximately constant volume at a rate permitting the formation and maintenance of polybutadiene in a concentration of at least 8 /3 Weight percent, but not in excess of 66 /3 weight percent in said reaction mixture exclusive of butadiene, the quantity of catalyst employed being not in excess or" 2.0 parts by Weight per 100 parts total butadiene iced employed, deactivating sodium metal, and recovering a clear low-color liquid polybutadiene polymer in dissolved form.

4. Process according to claim 3 in which styrene is admixed with the butadiene feed and a liquid butadienestyrene copolymer is produced.

References Cited in the tile of this patent UNITED STATES PATENTS 2,631,175 Crouch Mar. 10, I953 

1. A CONTINUOUS METHOD FOR THE PRODUCTION OF LIQUID POLYBUTADIENE WHICH COMPRISES CONTINUOUSLY MAINTAINING AN APPROXIMATELY CONSTANT VOLUME OF REACTION MIXTURE COMPRISING A HIGHLY AGITATED STABLE DISPERSION OF FINELY DIVIDED ALKALI METAL CATALYST HAVING AN AVERAGE PARTICLE SIZE OF LESS THAN 200 MICRONS IN A BODY OF LIQUID HYDROCARBON SOLVENT CONTAINING BUTADIENE AND POLYBUTADINE IN A CLOSED REACTION VESSEL AT A TEMPERATURE RANGING FROM 50 TO 100* C., INTRODUCING BUTADIENE, HYDROCARBON SOLVENT, AND CATALYST INTO SAID BODY OF LIQUID REACTION MIXTURE AND WITHDRAWING EQUIVALENT QUANTITIES OF REACTION MIXTURE THEREFROM TO MAINTAIN AN APPROXIMATELY CONSTANT VOLUME AT A RATE PERMITTING FORMATION AND MAINTENANCE OF POLYBUTADIENE IN A CONCENTRATION OF AT LEAST 81/3 WEIGHT PERCENT BUT NOT IN EXCESS OF 662/3 WEIGHT PERCENT IN SAID REACTION MIXTURE EXCLUSIVE OF BUTADIENE, THE QUANTITY OF CATALYST EMPLOYED BEING NOT IN EXCESS OF 2.0 PARTS BY WEIGHT PER 100 PARTS TOTAL BUTADIENE FEED EMPLOYED, DEACTIVATING ALKALI METAL IN SAID SOLUTION, AND RECOVERING A CLEAR LOW-COLOR LIQUID POLYBUTADIENE-POLYMER IN DISSOLVED FORM. 